Sandbox Express Checkout never creates transactions

[valley]

Hi there,
i'm writing a Rails Application and need to use PayPal Express
Checkout via ActiveMerchant to handle payments.
I've created 2 accounts in Sandbox, one business seller and one
personal buyer.
Everything seems to work fine, i.e. i'm redirected to PayPal after
getting the token, the buyer can do a purchase and after submitting (i
use useraction=commit) on PayPal the return_url is called successfully
on my Rails app, where i see success message.

But i never see any transactions created in the 2 accounts nor will
the notify_url be called (when trying with the IPN simulator it works
fine).

Can you tell me what i am missing or doing wrong ?
I've also tried in production mode, but there i do not see any
transactions as well.

This is my setup:

def checkout
setup_response = EXPRESS_GATEWAY.setup_purchase(50.00,
:ip => request.remote_ip,
:return_url => url_for(:action => 'confirm', :only_path
=> false),
:cancel_return_url => url_for(:action => 'error', :only_path =>
false),
:notify_url => url_for(:action => 'ipn', :only_path =>
false)
)
redirect_to EXPRESS_GATEWAY.redirect_url_for(setup_response.token)
+'&useraction=commit'
end


Thanks for helping me on that.
Best Regards
valley